The medical expenses for the previous 12 months were recorded and stored in columns 1 to 4 in c12-03. Projections for 2011, 2016, 2021,2026 and 2031 of the numbers of Canadians (in thousands) in each age category are listed above.
a) Determine the 95% confidence interval estimates of the mean medical costs for each of the four age categories.
b) For each year listed, determine the 95% confidence interval estimates of the total medical costs for Canadians 45 years old and older.